#! /usr/bin/env python
#
def sinus ( m ):

#*****************************************************************************80
#
## SINUS samples a noisy sine function.
#
#  Discussion:
#
#    For any given value of M, the same set of X and S will always be returned.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license.
#
#  Modified:
#
#    20 February 2019
#
#  Author:
#
#    John Burkardt
#
#  Parameters:
#
#    Input, integer M, the number of values desired.
#
#    Output, real X(M), S(M), abscissas and values for the noisy sine function.
#
  import numpy as np
#
#  R1 and R2 are the magnitudes of the two noise components.
#
  r1 = 0.1
  r2 = 0.1
#
#  Initialize the random number generator so that it always returns the same
#  set of values for a given value of M.
#
  seed = m + 123456789
  np.random.seed ( seed )
#
#  Choose M values X in [0,2pi].
#
  x = 2.0 * np.pi * np.random.rand ( m )
#
#  Evaluate S = sin(x) + scaled normal noise + uniform noise.
#
  s = np.sin ( x ) \
    + r1 * np.random.randn ( m ) * abs ( np.sin ( x ) ) \
    + r2 * ( 2.0 * np.random.rand ( m ) - 1.0 )
#
#  For convenience in plotting, sort by X value.
#
  ind = np.argsort ( x )
  x = x[ind]
  s = s[ind]

  data = np.zeros ( [ m, 2 ] )
  data[0:m,0] = x
  data[0:m,1] = s

  return data

def sinus_test ( ):

#*****************************************************************************80
#
## sinus_test tests sinus.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license.
#
#  Modified:
#
#    20 February 2019
#
#  Author:
#
#    John Burkardt
#
  import platform

  print ( '' )
  print ( 'sinus_test' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  sinus() evaluates a noisy sine function.' )

  for m in [ 9, 10, 9 ]:
    data = sinus ( m )
    print ( '' )
    print ( '  Input m = %d' % ( m ) )
    print ( '' )
    for i in range ( 0, m ):
      print ( '  %2d  %f  %f' % ( i, data[i,0], data[i,1] ) )
#
#  Terminate.
#
  print ( '' )
  print ( 'sinus_test' )
  print ( '  Normal end of execution.' )
  return

if ( __name__ == '__main__' ):
  sinus_test ( )